1. Field of the Invention
This invention relates to a method for preparing a lithium-aluminum alloy electrode for use in electrochemical cells incorporating such electrodes.
2. Description of the Prior Art
Lithium-aluminum alloys have been suggested as negative electrodes for electrochemical cells because of the highly electronegative nature of the lithium and the low atomic weight of the lithium-aluminum alloy. The combination of high electronegativity plus low atomic weight makes possible the construction of high energy density cells.
Several techniques are known for fabricating lithium-aluminum alloys for use as electrode materials.
One prior art technique for forming a lithium-aluminum electrode involves the electrochemical deposition of lithium onto a substantially pure aluminum electrode from a molten lithium salt bath. An example of such a process is set forth in U.S. Pat. No. 3,607,413.
Another technique for preparing lithium-aluminum alloys involves common metallurgical practices such as melting appropriate proportions of lithium and aluminum in an inert atmosphere and thereafter comminuting the cooled lithium-aluminum alloy so as to produce a finely divided powder. As an example of this technique see U.S. Pat. No. 3,957,532.
In yet another technique, a sandwich structure of lithium and aluminum sheets are heat soaked at temperatures close to the melting point of lithium while simultaneously applying pressure to the sandwich structure. See, for example, U.S. Pat. No. 3,981,743.
Each of the foregoing general techniques has some limitations and problems associated with it. In addition thereto, all of the above-mentioned techniques suffer from the disadvantage that considerable energy input is required in the formation of the alloy, in the form of thermal energy, electrical energy or both. Thus, there remains a need for a simple procedure for forming lithium-aluminum alloy electrodes which can be achieved at lower energy input.